---
layout: default
---
{% if page.use_mathjax %}
    {% include mathjax_support %}
{% endif %}
{% assign urlString = page.url | replace: "/", "," %}
{% assign strlist = urlString | split: "," %}
{% for x in strList %}
    <span>{{x}}</span>
{% endfor %}
<style>
    .crumbs {
        border-bottom: 1px solid black;
        margin-top: 4px;
        margin-bottom: 8px;
        display: flex;
        justify-content: space-between;
    }
    .crumbs ol {
        list-style-type: none;
        padding-left: 0;
    }

    .crumbs ol li {
        display: inline-block;
    }

    .crumb::after {
        display: inline-block;
        color: #000;
        content: '>';
        font-size: 80%;
        font-weight: bold;
        padding: 0 3px;
    }
    .chapter .title {
        text-align: center;
        font-size: 24px;
        font-weight: bolder;
        height: 2em;
        line-height: 2em;
        border-bottom: 2px double skyblue;
    }
    .work-area article {
        counter-set: Level1 {{ page.section | minus: 1 }};
    }
</style>
<nav class="crumbs">
    <ol>
        <li class="crumb">{{page.series}}</li>
        <li class="crumb">{{page.course}}</li>
        <li class="crumb">第{{page.chapter}}章</li>
        <li>第{{page.section}}节</li>
    </ol>
    <a href="/assets/lessons/{{ page.courseware }}" style="margin-right: 2em;">演示文稿</a>
</nav>
<article class="chapter">
     <div id="toc">
         <img class="toc-title" src="/images/bars-solid.svg" />
     </div>
    {{content}}
</article>
